PORTLAND – Luc Longley doesn’t know if he’ll have to retire. He doesn’t know if he’ll be able to make his way onto the Knicks’ playoff roster. He doesn’t know if his degenerative left-ankle injury that has required anti-inflammatories for years will allow him to play again this season.

The Aussie center does know a lot of things right now. But one thing he does know is that, since going on the injured list three weeks ago, the experiment of staying off the ankle and the pills hasn’t helped a bit.

He has come to the conclusion that if he is going to play again this season, he’ll have to start popping pills again. Stomach problems forced him to quit taking the pills eight weeks ago.

Whether he’s willing to make the sacrifice is a major question, as he wonders whether it’s worth it if he’s going to sit on the bench. Longley had 10 straight DNPs before going on the injured list March 6.

“I’m torn,” Longley said. “It’s a call I have to make. Of course I’m willing to do it if the team feels as though they need me to contribute. That hasn’t been the case this year. I haven’t contributed much this year.”

However, Longley’s 7-foot-2 frame and his low-post defense could come in handy during the playoff grind if the Knicks’ front line continues its pattern of lacking durability. Larry Johnson’s is back impaired; Kurt Thomas injured both ankles this season, and neither is 100 percent; and Marcus Camby is fragile overall. None of them are locks to make it through a long playoff run.

If Longley is not on the playoff roster, the Knicks’ insurance policy is Felton Spencer.

Longley will have another stomach exam when the Knicks return from the West Coast this week. If the tests are positive, he may begin taking the pills again and see if it helps the ankle. That is no guarantee, either.

“Obviously they want me to come back and play if I’m functional,” Longley said. “But even when I was taking them, I was struggling with it.”

Asked about the possibility of returning, Longley, who has three years left on his contract, said, “I hope it’s premature.”